summaryrefslogtreecommitdiffstats
path: root/drivers/char/ftape/zftape/zftape-read.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/char/ftape/zftape/zftape-read.c')
-rw-r--r--drivers/char/ftape/zftape/zftape-read.c377
1 files changed, 377 insertions, 0 deletions
diff --git a/drivers/char/ftape/zftape/zftape-read.c b/drivers/char/ftape/zftape/zftape-read.c
new file mode 100644
index 0000000..214bf03
--- /dev/null
+++ b/drivers/char/ftape/zftape/zftape-read.c
@@ -0,0 +1,377 @@
+/*
+ * Copyright (C) 1996, 1997 Claus-Justus Heine
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; see the file COPYING. If not, write to
+ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+ *
+ * $Source: /homes/cvs/ftape-stacked/ftape/zftape/zftape-read.c,v $
+ * $Revision: 1.2 $
+ * $Date: 1997/10/05 19:19:06 $
+ *
+ * This file contains the high level reading code
+ * for the QIC-117 floppy-tape driver for Linux.
+ */
+
+#include <linux/errno.h>
+#include <linux/mm.h>
+
+#include <linux/zftape.h>
+
+#include <asm/uaccess.h>
+
+#include "../zftape/zftape-init.h"
+#include "../zftape/zftape-eof.h"
+#include "../zftape/zftape-ctl.h"
+#include "../zftape/zftape-write.h"
+#include "../zftape/zftape-read.h"
+#include "../zftape/zftape-rw.h"
+#include "../zftape/zftape-vtbl.h"
+
+/* Global vars.
+ */
+int zft_just_before_eof;
+
+/* Local vars.
+ */
+static int buf_len_rd;
+
+void zft_zap_read_buffers(void)
+{
+ buf_len_rd = 0;
+}
+
+int zft_read_header_segments(void)
+{
+ TRACE_FUN(ft_t_flow);
+
+ zft_header_read = 0;
+ TRACE_CATCH(zft_vmalloc_once(&zft_hseg_buf, FT_SEGMENT_SIZE),);
+ TRACE_CATCH(ftape_read_header_segment(zft_hseg_buf),);
+ TRACE(ft_t_info, "Segments written since first format: %d",
+ (int)GET4(zft_hseg_buf, FT_SEG_CNT));
+ zft_qic113 = (ft_format_code != fmt_normal &&
+ ft_format_code != fmt_1100ft &&
+ ft_format_code != fmt_425ft);
+ TRACE(ft_t_info, "ft_first_data_segment: %d, ft_last_data_segment: %d",
+ ft_first_data_segment, ft_last_data_segment);
+ zft_capacity = zft_get_capacity();
+ zft_old_ftape = zft_ftape_validate_label(&zft_hseg_buf[FT_LABEL]);
+ if (zft_old_ftape) {
+ TRACE(ft_t_info,
+"Found old ftaped tape, emulating eof marks, entering read-only mode");
+ zft_ftape_extract_file_marks(zft_hseg_buf);
+ TRACE_CATCH(zft_fake_volume_headers(zft_eof_map,
+ zft_nr_eof_marks),);
+ } else {
+ /* the specs say that the volume table must be
+ * initialized with zeroes during formatting, so it
+ * MUST be readable, i.e. contain vaid ECC
+ * information.
+ */
+ TRACE_CATCH(ftape_read_segment(ft_first_data_segment,
+ zft_deblock_buf,
+ FT_RD_SINGLE),);
+ TRACE_CATCH(zft_extract_volume_headers(zft_deblock_buf),);
+ }
+ zft_header_read = 1;
+ zft_set_flags(zft_unit);
+ zft_reset_position(&zft_pos);
+ TRACE_EXIT 0;
+}
+
+int zft_fetch_segment_fraction(const unsigned int segment, void *buffer,
+ const ft_read_mode_t read_mode,
+ const unsigned int start,
+ const unsigned int size)
+{
+ int seg_sz;
+ TRACE_FUN(ft_t_flow);
+
+ if (segment == zft_deblock_segment) {
+ TRACE(ft_t_data_flow,
+ "re-using segment %d already in deblock buffer",
+ segment);
+ seg_sz = zft_get_seg_sz(segment);
+ if (start > seg_sz) {
+ TRACE_ABORT(-EINVAL, ft_t_bug,
+ "trying to read beyond end of segment:\n"
+ KERN_INFO "seg_sz : %d\n"
+ KERN_INFO "start : %d\n"
+ KERN_INFO "segment: %d",
+ seg_sz, start, segment);
+ }
+ if ((start + size) > seg_sz) {
+ TRACE_EXIT seg_sz - start;
+ }
+ TRACE_EXIT size;
+ }
+ seg_sz = ftape_read_segment_fraction(segment, buffer, read_mode,
+ start, size);
+ TRACE(ft_t_data_flow, "segment %d, result %d", segment, seg_sz);
+ if ((int)seg_sz >= 0 && start == 0 && size == FT_SEGMENT_SIZE) {
+ /* this implicitly assumes that we are always called with
+ * buffer == zft_deblock_buf
+ */
+ zft_deblock_segment = segment;
+ } else {
+ zft_deblock_segment = -1;
+ }
+ TRACE_EXIT seg_sz;
+}
+
+/*
+ * out:
+ *
+ * int *read_cnt: the number of bytes we removed from the
+ * zft_deblock_buf (result)
+ *
+ * int *to_do : the remaining size of the read-request. Is changed.
+ *
+ * in:
+ *
+ * char *buff : buff is the address of the upper part of the user
+ * buffer, that hasn't been filled with data yet.
+ * int buf_pos_read: copy of buf_pos_rd
+ * int buf_len_read: copy of buf_len_rd
+ * char *zft_deblock_buf: ftape_zft_deblock_buf
+ *
+ * returns the amount of data actually copied to the user-buffer
+ *
+ * to_do MUST NOT SHRINK except to indicate an EOT. In this case to_do
+ * has to be set to 0. We cannot return -ENOSPC, because we return the
+ * amount of data actually * copied to the user-buffer
+ */
+static int zft_simple_read (int *read_cnt,
+ __u8 __user *dst_buf,
+ const int to_do,
+ const __u8 *src_buf,
+ const int seg_sz,
+ const zft_position *pos,
+ const zft_volinfo *volume)
+{
+ TRACE_FUN(ft_t_flow);
+
+ if (seg_sz - pos->seg_byte_pos < to_do) {
+ *read_cnt = seg_sz - pos->seg_byte_pos;
+ } else {
+ *read_cnt = to_do;
+ }
+ if (copy_to_user(dst_buf,
+ src_buf + pos->seg_byte_pos, *read_cnt) != 0) {
+ TRACE_EXIT -EFAULT;
+ }
+ TRACE(ft_t_noise, "nr bytes just read: %d", *read_cnt);
+ TRACE_EXIT *read_cnt;
+}
+
+/* req_len: gets clipped due to EOT of EOF.
+ * req_clipped: is a flag indicating whether req_len was clipped or not
+ * volume: contains information on current volume (blk_sz etc.)
+ */
+static int check_read_access(int *req_len,
+ const zft_volinfo **volume,
+ int *req_clipped,
+ const zft_position *pos)
+{
+ static __s64 remaining;
+ static int eod;
+ TRACE_FUN(ft_t_flow);
+
+ if (zft_io_state != zft_reading) {
+ if (zft_offline) { /* offline includes no_tape */
+ TRACE_ABORT(-ENXIO, ft_t_warn,
+ "tape is offline or no cartridge");
+ }
+ if (!ft_formatted) {
+ TRACE_ABORT(-EACCES,
+ ft_t_warn, "tape is not formatted");
+ }
+ /* now enter defined state, read header segment if not
+ * already done and flush write buffers
+ */
+ TRACE_CATCH(zft_def_idle_state(),);
+ zft_io_state = zft_reading;
+ if (zft_tape_at_eod(pos)) {
+ eod = 1;
+ TRACE_EXIT 1;
+ }
+ eod = 0;
+ *volume = zft_find_volume(pos->seg_pos);
+ /* get the space left until EOF */
+ remaining = zft_check_for_eof(*volume, pos);
+ buf_len_rd = 0;
+ TRACE(ft_t_noise, "remaining: " LL_X ", vol_no: %d",
+ LL(remaining), (*volume)->count);
+ } else if (zft_tape_at_eod(pos)) {
+ if (++eod > 2) {
+ TRACE_EXIT -EIO; /* st.c also returns -EIO */
+ } else {
+ TRACE_EXIT 1;
+ }
+ }
+ if ((*req_len % (*volume)->blk_sz) != 0) {
+ /* this message is informational only. The user gets the
+ * proper return value
+ */
+ TRACE_ABORT(-EINVAL, ft_t_info,
+ "req_len %d not a multiple of block size %d",
+ *req_len, (*volume)->blk_sz);
+ }
+ /* As GNU tar doesn't accept partial read counts when the
+ * multiple volume flag is set, we make sure to return the
+ * requested amount of data. Except, of course, at the end of
+ * the tape or file mark.
+ */
+ remaining -= *req_len;
+ if (remaining <= 0) {
+ TRACE(ft_t_noise,
+ "clipped request from %d to %d.",
+ *req_len, (int)(*req_len + remaining));
+ *req_len += remaining;
+ *req_clipped = 1;
+ } else {
+ *req_clipped = 0;
+ }
+ TRACE_EXIT 0;
+}
+
+/* this_segs_size: the current segment's size.
+ * buff: the USER-SPACE buffer provided by the calling function.
+ * req_len: how much data should be read at most.
+ * volume: contains information on current volume (blk_sz etc.)
+ */
+static int empty_deblock_buf(__u8 __user *usr_buf, const int req_len,
+ const __u8 *src_buf, const int seg_sz,
+ zft_position *pos,
+ const zft_volinfo *volume)
+{
+ int cnt;
+ int result = 0;
+ TRACE_FUN(ft_t_flow);
+
+ TRACE(ft_t_data_flow, "this_segs_size: %d", seg_sz);
+ if (zft_use_compression && volume->use_compression) {
+ TRACE_CATCH(zft_cmpr_lock(1 /* try to load */),);
+ TRACE_CATCH(result= (*zft_cmpr_ops->read)(&cnt,
+ usr_buf, req_len,
+ src_buf, seg_sz,
+ pos, volume),);
+ } else {
+ TRACE_CATCH(result= zft_simple_read (&cnt,
+ usr_buf, req_len,
+ src_buf, seg_sz,
+ pos, volume),);
+ }
+ pos->volume_pos += result;
+ pos->tape_pos += cnt;
+ pos->seg_byte_pos += cnt;
+ buf_len_rd -= cnt; /* remaining bytes in buffer */
+ TRACE(ft_t_data_flow, "buf_len_rd: %d, cnt: %d", buf_len_rd, cnt);
+ if(pos->seg_byte_pos >= seg_sz) {
+ pos->seg_pos++;
+ pos->seg_byte_pos = 0;
+ }
+ TRACE(ft_t_data_flow, "bytes moved out of deblock-buffer: %d", cnt);
+ TRACE_EXIT result;
+}
+
+
+/* note: we store the segment id of the segment that is inside the
+ * deblock buffer. This spares a lot of ftape_read_segment()s when we
+ * use small block-sizes. The block-size may be 1kb (SECTOR_SIZE). In
+ * this case a MTFSR 28 maybe still inside the same segment.
+ */
+int _zft_read(char __user *buff, int req_len)
+{
+ int req_clipped;
+ int result = 0;
+ int bytes_read = 0;
+ static unsigned int seg_sz = 0;
+ static const zft_volinfo *volume = NULL;
+ TRACE_FUN(ft_t_flow);
+
+ zft_resid = req_len;
+ result = check_read_access(&req_len, &volume,
+ &req_clipped, &zft_pos);
+ switch(result) {
+ case 0:
+ break; /* nothing special */
+ case 1:
+ TRACE(ft_t_noise, "EOD reached");
+ TRACE_EXIT 0; /* EOD */
+ default:
+ TRACE_ABORT(result, ft_t_noise,
+ "check_read_access() failed with result %d",
+ result);
+ TRACE_EXIT result;
+ }
+ while (req_len > 0) {
+ /* Allow escape from this loop on signal !
+ */
+ FT_SIGNAL_EXIT(_DONT_BLOCK);
+ /* buf_len_rd == 0 means that we need to read a new
+ * segment.
+ */
+ if (buf_len_rd == 0) {
+ while((result = zft_fetch_segment(zft_pos.seg_pos,
+ zft_deblock_buf,
+ FT_RD_AHEAD)) == 0) {
+ zft_pos.seg_pos ++;
+ zft_pos.seg_byte_pos = 0;
+ }
+ if (result < 0) {
+ zft_resid -= bytes_read;
+ TRACE_ABORT(result, ft_t_noise,
+ "zft_fetch_segment(): %d",
+ result);
+ }
+ seg_sz = result;
+ buf_len_rd = seg_sz - zft_pos.seg_byte_pos;
+ }
+ TRACE_CATCH(result = empty_deblock_buf(buff,
+ req_len,
+ zft_deblock_buf,
+ seg_sz,
+ &zft_pos,
+ volume),
+ zft_resid -= bytes_read);
+ TRACE(ft_t_data_flow, "bytes just read: %d", result);
+ bytes_read += result; /* what we got so far */
+ buff += result; /* index in user-buffer */
+ req_len -= result; /* what's left from req_len */
+ } /* while (req_len > 0) */
+ if (req_clipped) {
+ TRACE(ft_t_data_flow,
+ "maybe partial count because of eof mark");
+ if (zft_just_before_eof && bytes_read == 0) {
+ /* req_len was > 0, but user didn't get
+ * anything the user has read in the eof-mark
+ */
+ zft_move_past_eof(&zft_pos);
+ ftape_abort_operation();
+ } else {
+ /* don't skip to the next file before the user
+ * tried to read a second time past EOF Just
+ * mark that we are at EOF and maybe decrement
+ * zft_seg_pos to stay in the same volume;
+ */
+ zft_just_before_eof = 1;
+ zft_position_before_eof(&zft_pos, volume);
+ TRACE(ft_t_noise, "just before eof");
+ }
+ }
+ zft_resid -= result; /* for MTSTATUS */
+ TRACE_EXIT bytes_read;
+}
OpenPOWER on IntegriCloud